EP1080313B1 - Radial bearing with a sliding bearing-type construction - Google Patents

Abstract

The invention relates to a radial bearing which can be used for bearing problems in which an angular displacement occurs during operation by virtue of the elastically flexible shaping of a bearing sleeve on which an elastically flexible bearing element with an essentially matrix-type fibrous structure is arranged.

Description

The invention relates to a radial bearing in sliding bearing design, in particular for use in centrifugal pumps, with one arranged on a shaft, transmitting torque designed bearing sleeve, which rotating within a bearing bush is arranged, wherein between the sliding parts a gap for a lubricant of low viscosity is located, the bearing sleeve of a Supporting element and a bearing element attached thereto and bearing thereon, and the support element in the area of the system of the bearing element different Has wall thicknesses.

In centrifugal pumps are various embodiments of shaft bearings known, depending on the medium to be transported various storage materials Find use. Ceramic bearing materials have proven to be particularly advantageous In bearings proved that with a medium of low viscosity, for example with water or alcohol, to be lubricated. A disadvantage of such Keramiklagem is their sensitivity to overheating due to lack of lubrication and jerky loads. Such exists in mixed friction area, if, for example, due to excessive radial loads, the sliding surfaces touch each other. Due to an excessive local entry of frictional heat into the ceramic Surfaces can form thermal stress cracks within the ceramic. As a result, there is a risk of a local heavy material overload, which as Result on the ceramic part cracks or pits arise and consequential damage is to be expected.

An additional load acts on such, from a stationary bearing bush and a rotating bearing sleeve existing storage, if between these parts, an angular offset occurs. For example, by DE-A-1 528 640 it is known in such bearings, the bushing against a housing To be arranged elastically by means of O-rings in order to achieve easy mobility.

Another solution is known from EP 0 492 605 A, from the nearest State of the art is assumed. This shows a ceramic bearing element, which with the interposition of a in the range of the inner diameter attached rubber element positively connected to a profiled shaft is. The shaft may have a cross-sectional profile, which as a wedge, hexagon, Zweiflach or the like is formed. For positive force transmission has the rubber element in the region of its inner diameter over a Shaping, which corresponds to the negative shape of the wave. Thus, that exists Rubber element in a sense of adjacent cylinder sections, wherein each cylinder section has a different cross section, but in the longitudinal direction the wave remains constant. As on both ends of the shaft bushing Disks are arranged, the rubber element between the ceramic bush, the Discs and the profiled shaft chambered arranged.

For large multi-stage pumps or long shafts with interposed Storage, for example, in large feed pumps, borehole pumps or on flying bearings with unilateral shaft overhang, occur due to the Operation prevailing forces inclinations or deflections of the shaft on. As a result, the bearing sleeve rotating with the shaft also takes one Inclination. A resulting one-sided bearing load represents a further endangerment for ceramic materials which are sensitive to impact or shock loads Stock.

The invention is therefore based on the problem of a fragile materials to develop using shaft bearing, the one occurring in storage Angular offset allows.

The solution to this problem provides that a predominantly arranged in a matrix fiber structure with ceramic or arranged therein Carbon parts, the bearing element forms that a ceramic or carbon matrix the fiber structure forms that the support element is equal to or longer than the bearing element is formed and that of a wall thickness maximum in the middle Area of the support element, the wall thickness in the direction of the end faces of the bearing element is formed decreasing.

Viewed in longitudinal section, the support element has a wall thickness curve, the has a maximum in the middle area and from there to both sides is designed decreasing. On the support element that is a predominantly matrix-like Fiber structure having ceramic or carbon bearing element with pressed a shrink or press fit. The dimensions and tolerances of individual parts are chosen so that when temperature influences the bearing element remains firmly connected to the support element. The combination of such a bearing element with a support element having an elasticity gives the advantage that when an angular offset occurs, both parts react elastically yielding and thus a risk of breakage on the bearing element is prevented. The predominantly matrix-like arranged fiber structure, which is formed as a ceramic or carbon matrix is, in which ceramic or carbon parts are embedded, in contrast to a monolithic component a compliance against bending loads on. Depending on the desired bearing pairing can be in a carbon matrix both ceramic and carbon parts are arranged. same for also for a ceramic matrix.

Thus, it is possible for such bearing elements which are intrinsically susceptible to breakage and which have been produced as sintered parts, a more resistant to tensile stresses occurring during bending loads Property to be generated. The at a bending load in a sleeve cross-section such a bearing element occurring, fracture-end tensile stresses are compared to a pure by the fibers arranged like a matrix Sintered material improved by a factor of 10. This allows angular deviations compensate the storage.

Is the bearing element connected by a shrink connection with the support element, Thus, the shrinking forces of the bearing element cause the formation of a light crowned shape in the joined state. As the support element according to an embodiment the invention in that area in which the ends of the bearing element have a substantially thinner wall thickness than in its middle region, cause the shrinkage forces in the range of thinner wall thicknesses Diameter reduction. A shrunk bearing bush with its predominantly matrix-like fiber composite, for example made of Siliziumkarbidfasem or carbon fibers, thus has a slightly convex surface, which compensates for angular deviations of a shaft bearing equipped therewith supported. The combination of the equipped with a matrix-like fiber structure Bearing element with the support element whose shape to a Spring characteristic leads around the radial axis, ensures an angle error compensating Elasticity. When pressed bearing elements ensures only the elastic Yielding the compensation of angular deviations.

Further embodiments of the invention are described in the subclaims. The rotating part of the radial bearing, the bearing sleeve, form the support element and the bearing element mounted thereon. In a middle area of the bearing element the support element is provided with a wall thickness maximum, wherein the dimensions are chosen so that thus a secure transmission of forces is ensured. Furthermore, the area of the wall thickness maximum serves to accommodate rotary movements transmitting means between shaft and support element. In the range of the end faces of the bearing element wall thickness minima are provided on the support element. They support the spring action of the support element and the training a spherical shape of the bearing surface.

In the area of the end faces of the support element, at least one thick-walled, on provided the shaft zoomed end portion, said end portion is arranged at a distance from the end face of the bearing element. In between is the Wall of the support element as an elastically resilient, thin-walled section educated. The arranged in the region of the end face of the support element thick-walled End section can also torque-transmitting or force-transmitting Embodiments have. To bear the bearing element, the support element have an end bearing surface.

The feature according to which the end faces of the support element over the end faces of the Outstanding bearing element, reduces the occurrence of voltage spikes and allows a positive influence on the spring characteristic. Due to the arrangement of a Free space between the shaft and the support element in the area of one or Both end faces of the bearing element is a place for elastic compensation created by angle errors.

Fig. 1 - 3

verschiedene Ausführungsformen des Tragelementes, die

Fig. 4

die Anordnung eines solchen Tragelementes in einem Lager ohne Win- kelversatz, die

Fig. 5 u. 6

die Anordnung eines Tragelementes beim Auftreten eines Winkel- versatzes sowie ein zugehöriges Tragbild und die

Fig. 7 u. 8

bei einer konventional ausgebildeten Lagerung analoge Darstellungen zu den Fig. 5 und 6.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. It show the

Fig. 1-3

various embodiments of the support element, the

Fig. 4

the arrangement of such a support element in a bearing without angular misalignment, the

Fig. 5 u. 6

the arrangement of a support element when an angular offset occurs and an associated contact pattern and the

Fig. 7 u. 8th

in a conventionally designed storage analogous representations to FIGS. 5 and 6.

Fig. 1 shows in longitudinal section a support element 1, which metallic or non-metallic May be of the mid-range as Section 2 with maximum Wall thickness is formed. This section 2 is for transmitting torques trained and used for this known means 3, for example, tongue and groove connections. From the middle section 2 from the wall thickness of the support element 1 to the end faces 4, 5 towards increasingly thinner. Such a wall thickness course has a course without sharp-edged transitions. On the outside diameter of the support element 1, a bearing element 6 is fixed, which consists of consists of a predominantly matrix-like arranged fiber structure, wherein a ceramic or carbon matrix forming the fiber structure. Embedded in the matrix Ceramic or carbon parts. The axial length of the bearing element 6 is the same or shorter than the axial length of the support element 1 is formed. The end faces 7, 8 of the bearing element 6 are opposite the end faces 4, 5 of the support element. 1 set back. Such a measure prevents the transition between these two parts the occurrence of voltage spikes.

The middle section 2 of the support element 1 provides a web-like connection to Wave forth. Starting from the section 2 is the wall thickness of the support element. 1 designed decreasing towards the front sides 4,5. Such a form, a free space between a surface 9 of a shaft and the support element 1 produces, can in simple manner, for example by machining, be generated.

In Figs. 2 and 3, other embodiments are shown which are also elastic Ensure properties of a bearing sleeve thus formed. You can at larger radial forces to be used. The axial length of the support element 1 is enlarged compared to the embodiment of FIG. The area the end faces 4, 5 of the support element 1 was designed so that an approximation to the surface 9 of a shaft, not shown, takes place.

The shaft surface 9 opposite surfaces 10, 11 of the end faces 4, 5 of the Supporting element 1 are arranged in Fig. 2 to form a gap. That exists the possibility of bending under the influence of radial forces of the support element 1 by the game shown between the surfaces 10, 11th and the surface 9 to influence. By suitable selection of the dimensions for a clearance to be provided between these parts is simply a Limiting the deflection possible. A thin-walled section 12, 13 of Supporting element 1, between the end faces 7, 8 of the bearing element 6 and the End faces 4, 5 of the support element 1 is arranged, ensures the suspension properties a bearing sleeve of a radial bearing thus formed. By means of such Measure is the formation of a progressive spring characteristic possible.

In the illustration of Fig. 2 is on the right side in the region of the end face 4 a another course of the opposite with a surface 11 of the shaft surface 9 End of the support element 1 drawn. The transition 13 is drawn here conically, but there are also other transitions in the form of sheets o. The like. Possible. Such a design is advantageous in a mounting of such a warehouse and allows easier insertion. In the illustration of FIG. 2, the left side is the front side 5 designed so that the support element on the for a torque transmission necessary means 3 can be pushed.

The modification of Fig. 3 provides torque transmitting means 3 only in the area the front side 5 of the support element 1 in front. To transfer to the bearing element 6 acting bearing forces is the support element 1 in the area 2 and with the surfaces 10, 11 on the surface 9 of a shaft. It is essential that between the length of the bearing element 6 limiting end faces 7, 8 and the Surfaces 10, 11 of the support element 1, a thin-walled portion 12, 13 exists. One such section, as can also be seen in Fig. 2, ensures the compliance such a unit.

Although the embodiments of FIGS. 1 to 3 show an identical length of the bearing element 6; however, the invention is not limited thereto. Their advantages can be achieved by other lengths of the bearing element 6.

In Fig. 4 is a mounted bearing design exemplified using the Components of Figure 1 shown. On a shaft 14 is a support member 1 due to Means 3 arranged to transmit torque. A shrunk on the support element 1 Bearing element 6 cooperates with a bearing bush 15. It is shown as the end, thin-walled ends of the support element 1 under the Influence of the shrinkage forces obtained a spherical shape and extend to the shaft 14 out. Furthermore, it will become thinner in connection with the front side Wall thickness course allows elastic compliance and thus the prerequisite for a compensation of an angular offset of the shaft 14 against the bushing 15 ensures.

Figs. 5 and 6 show a radial bearing according to the invention and the compensation of angular deviations. In Fig. 5 is opposite to a stationary bearing bush 15 inclined by the angle β, from support element 1 and bearing element. 6 existing bearing sleeve shown, which rotates with a shaft 14. The associated perspective Representation of FIG. 6, a plan view of an under force deformed bearing sleeve, shows a large contact surface 16. This is between the bearing bush 15 and the bearing element 6 is formed. As a result of under stress itself forming spherical shape of the bearing element 6, the deformation leads at lighter Inclination to an adaptation of the adjacent sliding surfaces. By the Enlargement of the bearing surface 16 is, with the same radial force, one on the bearing element 6 local surface pressure significantly reduced. Consequently Such a designed radial bearing is much less sensitive against jerky or beating as well as rubbing loads, as a rigid one Elements existing warehouse.

FIGS. 7 and 8 show, analogously to the illustration to FIGS. 5 and 6, a bearing according to FIG the state of the art. At an angular displacement β of a monolithic ceramic Bearing sleeve 18 results in an inclined position only shown in Fig. 8 very narrow storage area 17. Compared to a whole-area installation of the areas in an operation without inclination, causes an inclination he Significant reduction of the usual storage space. The on the camp acting radial force is thus distributed over a much smaller area. Consequently, the surface pressure acting on the bearing element and / or exceeds the local friction power the permissible values. The previously used for such storage monolithic bearing sleeves in the form of ceramic materials due to their shredding sensitivity neither shrunk nor otherwise under tension may be set are overloaded in such an operating condition. In order to their purpose is considerably limited.

Claims (8)

1. Radial bearing of the sliding-bearing type, in particular for use in centrifugal pumps, with a bearing sleeve arranged on a shaft (14) and designed to transmit torque, the bearing sleeve being arranged rotatably within a bearing bush (15), a gap for a low-viscosity lubricating medium being located between the parts sliding on one another, the bearing sleeve consisting of a carrying element (1) and of a bearing element (6) fastened to and bearing against the latter, and the carrying element (1) having different wall thicknesses in the region of bearing contact of the bearing element (6), characterized in that a fibrous structure arranged predominantly in a matrix-like manner and having ceramic or carbon particles arranged in it forms the bearing element (6), in that a ceramic or carbon matrix forms the fibrous structure, in that the carrying element (1) is designed to be equal to or longer than the bearing element (6), and in that the wall thickness is designed to decrease from a wall-thickness maximum in the middle region (2) of the carrying element (1) in the direction of the end faces (7, 8) of the bearing element (6).
2. Radial bearing according to Claim 1, characterized in that, in a middle region of the bearing element (6), the carrying element (1) is provided with a wall-thickness maximum.
3. Radial bearing according to Claim 2, characterized in that force-transmitting means (3) are arranged in the region (2) having a wall-thickness minimum.
4. Radial bearing according to Claims 1, 2 or 3, characterized in that the carrying element (1) is provided with wall-thickness minima in the region of the end faces (7, 8) of the bearing element (6).
5. Radial bearing according to one or more of Claims 1 to 4, characterized in that the carrying element (1) has a thin-walled portion (12, 13) between at least one thick-walled end portion (10, 11) in the region of its end faces (4, 5) and an end face (7, 8) of the bearing element (6).
6. Radial bearing according to one or more of Claims 1 to 5, characterized in that the bearing element (6) bears on an axial face of the carrying element (1).
7. Radial bearing according to one or more of Claims 1 to 6, characterized in that the end faces (4, 5) of the carrying element (1) project beyond the end faces (7, 8) of the bearing element (6).
8. Radial bearing according to one or more of Claims 1 to 7, characterized in that one or more free spaces are arranged between the carrying element (1) and a shaft surface (9) in the region of the end faces (7, 8) of the bearing element (6).

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